I had this same problem last year! I went to change the picks on my Vipers after a few seasons of usage and I couldn't get the bolt to budge. Got out the compressor and impact wrench and it popped right off.
Use a penetrant like Liquid Wrench or PB (works better than WD40). Spray on liberally, let sit for a day, and hit it again. You can also tap the wrench with a hammer as you're trying to loosen it. Once you get the bolts loose, you can then lube them or put anti-seize paste on them.